Fabrication of hollow articles



April 7, 1964 w. v, wENGER 3,127,860

FABRICATION OF HOLLOW ARTICLES Filed June 25, 1959 5 Sheets-Sheet 1 v r//,V i a" Q; 111 1 I i 1 In:

I I I l I L i L :I: l/W/W .4 5 \S FIG. 3 sq -4o FIG. 4

INVENTOR.

WILLIAM VERNON WENGER April 7, 1964 w. v. WENGER 3,127,860

FABRICATION OF HOLLOW ARTICLES Filed June 23, 1959 5 Sheets-Sheet 2:

FIG. 2

Q INVEN TOR. WILLIAM VERI\10N WENGER ATTORNEYS April 7, 1964 w. v.WENGER 3,127,860

FABRICATION OF HOLLOW ARTICLES 5 Sheets-Sheet 3 Filed June 23, 1959 FIG.5

INVENTOR. WILLIAM VERNON WENGER ATTORNEYS April 7, 1964 w. v. WENGER 3,

.FABRICATION OF HOLLOW ARTICLES Filed June 23, 1959 5 Sheets-Sheet 4FIG.7

INV.ENTO R.- WILLIAM VERNON WENGER BYW t ATTORNEYS Ap 7, 1964 w. v.WENGER 3,127,860

FABRICATION OF HOLLOW ARTICLES Filed June 23, 1959 5 Sheets-Sheet 5 FIG.8

INVENTOR.'

WILLIAM V NON WENGER W gfE -uagyflfi A TTOP/VEYS United States Patent O3,127,866 FABRICATION OF HOLLOW ARTICLES). William Vernon V/enger,Alton, Ill., assignor to Glin Mathieson Qhernical Corporation, EastAlton, 111., a corporation of Virginia Filed Jane 2.3, H93, Ser. No.822,299 6 Claims. (Cl. 113-44) This invention relates to the fabricationof hollow articles by expansion of sheet-like material and moreparticularly to a novel means for controlling the amount of expansionfrom each face of the aforesaid sheet-like articles.

The hollow sheet-like material preferably in the form of sheet metalpanels may be fabricated in accordance with various methods but are mostadvantageously and preferably made by a process such as described in US.Patent No. 2,690,002, issued to Grenell on September 28, 1954.

in accordance with the process of the aforesaid patent to Grenell, apattern of weld-inhibiting material is applied to a clean surface of asheet of metal. A clean surface of a second sheet of metal issuperimposed on this surface and the two sheets are secured to preventrelative movement between each other and then pressure-welded together,as by hot rolling, in their adjacent areas which are not separated bythe weld-inhibiting material. Hot rolling of the sheets results inreducing the thickness of the two sheets and elongating he resultantblank in the direction of rolling while the width of the resultant blankremains substantially the same as the initial width of the sheets.Following the pressurewelding operation, the resultant blank can besoftened as by annealing to shake it more pliable, and if desired, itmay then be cold rolled to final gauge and again softened as byannealing. The application of weld-inhibiting material results in anunjoined portion of a pattern of laminations between the outer faces ofthe pressure-welded blank. Any time after pressure-Welding of the blank,and preferably after softening by annealing, the unjoined portion orpattern of laminations is distended by injecting therein a fluidpressure of suflicient magnitude to permanently expand the blank in thearea of the unjoined portion or pattern of laminations to form a desiredcorresponding system of passageways.

One method of expanding a blank may be accomplished by subjecting theblank to external confinement between at least one rigid die member anda body of fluid, under pressure, applied externally to only one side ofthe blank. One of the rigid die members in the form of a press platenwith a suitably shaped die surface, such as a flat one in particular, onone side of the blank while the fluid, and preferably a suitableincompressible liquid, such as water, oil or the like, acts on the otherside of the blank so as to constrain it between the die surface and thefluid or liquid during the application of a blankexpanding fluidpressure injected internally of the blank into the unjoined portion orpattern of laminations. This fluid or liquid acting externally of theblank may be contained within a recess or cavity in a second rigid diemember to act in conjunction therewith to control the height and theshape of the expanded portions of the blank. Such second rigid diemember is ordinarily recessed to a depth corresponding to the finalheight of the distention desired in the expanded portions of the blank.

Automatic control means have been proposed for the above method ofexpanding a blank by which the blankexpanding pressure would be injectedwithin the unjoined portion or pattern of laminations in response to apredetermined blanloholding pressure, in the recess or cavity of thesecondary die, which acts upon an external sur- 3,127,860 Patented Apr.7, 1964 face of the blank to constrain its other surface against theflat or recessed platen. In turn, a means responsive to a predeterminedpressure level of the blank-expanding pressure automatically releasesboth the blank-holding and blank-expanding pressure. However, inherentvariables both in the initial method of fabricating the blank and in theaforesaid means for expanding the resultant hollow blank resultmalformations occurring in the expanded blank. Such malformationsinclude failure to obtain a substantially flat panel and in a lack ofuniform crosssectional configurations extending throughout the unjoinedportion or partial laminations in the blank.

hese malformations are caused as a result of a plurality of variableseach adding to resultant total malformations of the expanded blank. Forexample, in the initial application of the pattern of weld-inhibitingmaterial, it is difiicult to control the application of weldinhibitingmaterial so that a uniform thickness thereof is obtained uniformlythroughout the pattern. This results in pinpoint welding within the areaof the applied pattern of weld-inhibiting material in what is commonlyknown as tacking to produce small points of weakstrength welds. Duringexpansion these pin-point welds require a certain degree of pressure tobreak these areas loose. Accordingly, where release of the expandingoperation is dependent on a predetermined pressure level within thehollow blank, this pressure level may be reached before this tacked areabreaks lose causing release of the blank-holding and blank-expandingpressures before the tacked area becomes fully expanded after breakingloose.

Also some of these hollow blanks are provided with a system oflaminations having a pattern requiring very narrow and restricted areas.This means that the high pressure, blank-expanding, can build up betweena point of entry into the laminations and the restricted area, ofttimesreaching an actuating pressure level which releases the variouspressures before the laminations beyond the restriction are fullyexpanded.

Also these partially laminated blanks are not uniformly flat prior toexpansion since irregularities occur therein as for example those whichresult from manual handling of the blank. Such departure in flatness isgenerally intended to be removed by the blank-holding pressure whichforces the panel flat against the rigid die having the shaped surface,i.e., a flat surface. Thus, when the partially laminated blank is ofheavy gauge it has been found that the application of a fluid pressureis required for an appreciable time interval in order to move it andhold it firmly in contact with the shaped surface of the die. However,if conventional teachings are followed so that the operating sequence isdependent on a preceding pressure level, activation of theblank-expanding pressure is reached before heavy gauged partiallylaminated blanks are completely moved in intimate contact with theshaped surface of the die. Where this happens, it causes prematureactivation of the blank-expanding pressure be ginning expansion of theblank before the heavy gauge metal is moved into intimate contact withthe shaped surface die.

Malformations are also caused by fluctuations of fluid pressure in thelabyrinth of conduits usually found in conventional presses. Thesefluctuations can result from rearrangement of fluid flow and pressures.during various value arrangements. Thus, for example, when the desiredactivating level of the blank-holding pressure is reached, although itmay actuate the blank-expanding pressure operation, it often also causesa reduction in the level of the blank-holding pressure before the heavygauge blank is moved in contact with the shaped surface die at the timewhen expansion of the blank occurs.

Accordingly, it is an object of this invention to eliminatedisadvantages of the prior art.

Another object of this invention is to provide a novel means for theapplication of fluid pressure to enable a more exacting control for theexpansion of hollow articles.

A still another object of this invention is to provide a novel means forthe application of controlled pressures for producing an improved hollowarticle.

A still another object of this invention is to provide a novel means forthe application of controlled pressures for producing expanded hollowarticles having a more uniform cross-sectional configuration throughoutthe extent of its hollows.

A still another object of this invention is to provide a novel means forthe application of pressures for controlling the degree of expansion outof each face of a partially laminated sheet.

A still another object of this invention is to provide a novel means forthe application of controlled pressures for producing an improved hollowpanel in which the distention occurs on one side only while the otherside remains undistended and substantially smooth or flat.

A further object of this invention is to provide a novel means forobtaining an improved hollow panel having a high degree of smoothnessand flatness and in which its expanded unjoined hollow portions havethroughout a more uniform cross-sectional configuration.

A still further object of this invention is to provide a novel means forthe application of controlled pressures to produce a novel hollowarticle in which one side is distended to a substantially lesser degreethan the other side and in which the expanded hollow portions, of thearticle, have throughout a more uniform cross-sectional configuration.

Other objects and advantages will become more apparent from thefollowing description and drawings in which:

FIGURE 1 is a plan view partly in section of a suitable blank from whicha hollow panel is to be formed in accordance with this invention;

FIGURE 2 is a partially sectional View in elevation and a partiallyschematic view of one embodiment of this invention;

FIGURE 3 is a fragmentary sectional view in elevation illustrating aportion of the blank taken along lines III- III of FIGURE 1 expanded inaccordance with this invention;

FIGURE 4 is a partially sectional and schematic View of a means ofmodifying the apparatus of FIGURE 2 in accordance with anotherembodiment of this invention;

FIGURE 5 is a partially sectional view and a schematic view of anapparatus illustrating another embodiment of this invention;

FIGURE 6 is a fragmentary sectional view in elevation illustrating aportion of a blank taken along lines IIIIII of FIGURE 1 expanded into anovel panel in accordance with one aspect of this invention;

FIGURE 7 is still another partially sectional view in elevation and apartially schematic view illustrating an apgaratus of still anotherembodiment of this invention; an

FIGURES 8 and 9 are still further partially sectional views in elevationand partially schematic views illustrating additional apparatus offurther embodiments of this invention.

Referring to the drawings a suitable form of a blank 1 is shown inFIGURE 1 and includes a particular configuration of internally unjoinedor partially laminated area 2 which extends to a peripheral edge of theblank at 3. The unjoined area is contained between solid portions 4 and5. Although the simplest of configurations has been illustrated inFIGURE 1, the hollow or partially laminated blank contemplated to befabricated in accordance with this invention can be expanded fromvarious suitable blanks such as that disclosed in the aforesaid US.Patent No. 2,690,002 and can be of any shape such as a flat or curvedsheet, a cup, a cone or other surface of revolution. For a specificexample, a 0.060 inch thick blank having a more complex system ofunjoined areas or laminations was fabricated from 1100 type aluminumcontaining a system of passageways inch in width. The laminations inthis blan k can be spaced an equal distance from the faces of the blankso that the complementary portions of the blank adjacent the unjoinedarea are each 0.030 inch thick. This blank, an equivalent of the blankillustrated in FIG- URE 1, can then be placed on the flat shaped surface6 or a die 7.

Die 7 has extending from its lower surface an integral piston 8 receivedin a bore or piston chamber 9 of a hydraulic cylinder 10. Activation ofdie 7 is obtained by a fluid pressure injected into piston chamber 9 ofhydraulic cylinder 10 by means of a fluid conduit 11 connected at oneend in communicating relationship with piston chamber 9 and at its otherend to a common fluid conduit 12. Fluid conduit 12 is providedsequentially with a pressure switch 13, a valve 14, a check valve 15 anda pressure regulator 16. As illustrated, valve 14 is placed betweencomplementary fluid conduit portions 87 and 88 of fluid conduit 11.Venting for piston chamber 9 is accomplished by means of a conduit 17connected at one end into fluid conduit 11 at any point adjacenthydraulic cylinder '10. Fluid conduit 17 also exhausts into theatmosphere through a manually operated valve 18. However, it is to beunderstood that piston chamber 9 may be vented by conduit 17 so as toreturn the source of high pressure fluid 19. The common fluid conduit 12is connected to a source of high pressure fluid -19.

Pressure regulator 16 reduces the pressure level conduit 12 to anappropriate pressure required for operating die 7, for example 3,000p.s.i. (pounds per square inch) for purposes of the above-referred-tospecific example and hereinafter referred-to as the specific example.

Valve 14 is maintained normally in a closed position, betweencomplementary fluid conduit portions 87 and 88 of fluid conduit 11 untilactuated by solenoid 20 which simultaneously closes a normally openelectric switch 21. Solenoid 20 is grounded at one end 22 and isconnected at the other end through a common juncture 23 to a terminal 24of a manually operated push button switch 25. The other terminal 26 ofpush button 25 is connected through a common juncture 2'7 to a source ofelectrical energy. Electrical switch 21 has one terminal 35 connected tocommon juncture 23 and has its other terminal 36 connected through aterminal 28 to an electric switch 29 normally in a closed position untilactuated into the open position by solenoid 30, which is connected atone end to a ground 31 and at its other end by means of an electricconduit 32 to a common juncture 33. The other terminal 34 of electricalswitch 2% is connected to juncture 27, which with terminal 25 of pushbutton 25 is connected to any appropriate source of electrical energy.

Pressure switch 13, in fluid conduit 11, is a conventional electricaltype of switch adapted to provide a momentary means of transmitting anactivating signal and has one terminal connected through an electricalconduit 37 to a source of electrical energy with its other terminalconnected by means of an electric conduit 38 to a common juncture 39.Pressure switch 13 is preset so as to be activated at a predetermineddie closing fluid pressure in conduit 11 or piston chamber 9, forexample 2,500 psi. in order to electrically energize the circuit throughjuncture 30 for the specific example.

Fixedly mounted against movement above die 7 and panel 1 is an upper die40 having in its lower face a suitable chamber or cavity 41. An integralperipheral ridge 4-2 surrounds die recess or cavity 41 and is providedin its lower surface 4-3 with a suitable sealing means such as an O-ring44 for fluid-tight engagement with the top surface of partiallylaminated blank 1 upon raising die 7 from its open to its closedposition. Die 40 is adapted for injection of a fluid pressure therein bymeans of a fluid conduit 45 in communicating relationship with diechamber or cavity 41. The other end of fluid conduit 45 is connectedthrough a momentary contact pressure switch 46, valve 47, check valve 48and pressure regulator 49 to a header conduit 50, which header conduitis in turn connected into the common conduit 12. Pressure regulator 19reduces the level of the fluid pressure from header conduit 50 to thedesired blank-holding fluid pressure, such as 850 psi. for the specificexample, into the die chamber or cavity 41 to hold blank 1 down againstthe shaped surface 6 of die 7.

Valve 47 is a three-way valve normally maintaining a closed positionbetween complementary fluid conduit portions 8) and 90 of fluid conduit45 and also normally maintaining complementary fluid conduit portion 89in communicating relationship with vent conduit 52 until actuated bysolenoid 51. In its normal position valve 47 maintains die cavity orrecess 41 vented to the atmosphere, drain or to any appropriate meansreturning fluid back to the source of high fluid pressure 19. Uponactuation of solenoid 51, valve 47 establishes a closed relationshipbetween the complementary fiuid portion 89 and vent conduit 2, andplaces complementary fluid portions 89 and 90 in communicatingrelationship with one another.

Solenoid 51 simultaneously with the actuation of valve 47 also closes anelectrical switch 53 normally in the open position. Solenoid 51 isfurther connected at one end to a ground 54 and at its other end througha common juncture 39, electrical conduit 38 to pressure switch 13. Oneterminal 55 of electrical switch 53 is also connected to common juncture39 and the other terminal 56 is connected by an electrical conduit 57 toa terminal 53 of electrical switch 59 whose other terminal 60 isconnected to a source of electrical energy. Switch 59 is normallymaintained in a closed position until actuated into an open position bymeans of a solenoid 61 having one end grounded at 62 and its other endconnected through an electrical conduit 63 to a juncture 33.

As indicated above, fluid conduit 45 is also provided with a momentarycontact pressure switch 46. This pressure switch 46 is adapted to beactuated in response to a predetermined pressure level, such as 850 psi.for purposes of the specific example, to activate a delay timer 64adapted to transmit a signal after a predetermined time delay, forexample 3 seconds for purposes of the specific example, to provide asource of electrical energy through an electrical conduit 65 to solenoid66. Also, as the pressure in die chamber 41 builds up to 850 p.s.i., thedieclosing pressure reaches its maximum pressure of 3000 Ablank-inflation fluid is applied internally of blank 1 by means of afluid conduit 67 connected at one end in communicating relationship withthe laminations or unjoined areas 2 of blank 1 and at its other endthrough a momentary contact switch 63, valve 69, check valve 70, andpressure regulator 71 to header conduit Sti. Pressure regulator 71reduces the level of high pressure in header conduit 50 to the pressurelevel desired for inflation of blank 1, such as 2800 p.s.i. for purposesof the specific example. Valve 69 is adapted to control a flow of fluidbetween complementary portions 91 and 92 of fluid conduit a7 and a ventconduit 72 which may be vented to the atmosphere or to an appropriatemeans to return the blank-expanding fi id back to the source of highpressure fluid 19. Normally valve 69 is maintained in a closed positionrelative to the complementary portions 91 and 92 of fluid conduit 67with complementary portion 91 in communicating relationship with vent 72until actuated by solenoid 66 which simultaneously closes a normallyopen switch 73.

Solenoid 66 is grounded at one end 7 4 and connected at the other endthrough a common juncture 75 to the electrical conduit 65. Switch 73 hasone terminal 76 con nected to common juncture 75 and its other terminal96 connected through an electrical conduit 77 to a terminal '78 of anelectrical switch 79 normally maintained the closed position untilactuated by solenoid 80. The other terminal 81 of electric switch 79 isconnected through an electrical conduit 82 to a source of electricalenergy. Solenoid 30 is adapted to be activated by having its one endgrounded at 83 and its other end connected through an electric conduit84 to a common juncture 33.

The momentary contact pressure switch 68, in fluid conduit 67, isadapted to be actuated at a predetermined pressure level, such as 2800pounds for purposes of the specific example, to energize a delay timer35, which after a predetermined time delay, for example 10 seconds forpurposes of the specific example, provides a source of electrical energythrough electrical conduit 86 to the common juncture 33.

In operation with valve 18 in vent conduit 17, in the closed position,blank 1 and particularly the 1100 type aluminum blank of the specificexample referred to above, is placed on the shaped surface 6 of die "7.Thereafter, the functions of the apparatus are initiated by manuallydepressing push button switch 25 which energizes solenoid 26' to openvalve 14 and to close the electrical switch 21. Solenoid 20 is keptenergized by means of the normally closed pressure switch 2% so as tomaintain a complete circuit with a source of electrical energy atjuncture 27 and ground 22. With valve 14 in the open position, adie'closing pressure reduced to a desired level, such as 3,000 p.s.i.for the specific example, by means of pressure regulator 16, is injectedinto piston chamber 9 to urge piston rod 8 together with die 7 upwardlyinto the closed position Whereat blank 1 is placed therebetween insealin g relationship with die recess or cavity 41 by means of theO-r-ing 44. When the die-closing pressure in piston chamber 9 reaches apredetermined level, for example 2,500 psi. for the specific example,pressure switch 13 is momentarily actuated to enengize solenoid 51 toclose the ccmplementmy fluid conduit portion 89 relative to vent conduit5'2 and to place it in communicating relationship with complementaryfluid conduit portion 90 and header conduit 5% While simultaneouslyclosing switch 53. With the closure of switch 53, a complete electricalcircuit is established between ground 54 and source of electricalenergy, at terminal tit} of switch 59, to maintain solenoid 51 activateduntil the circuit is broken upon energization of solenoid s1.

With the complete fluid conduit 45 placed in communicating relationshipwith header 50, a blank-holding pressure reduced to an appropriatepressure level by means of pressure regulator 49, such as 850 psi. forpurposes of the specific example, is injected into die chamber or cavity41. As fluid pressure in die chamber or cavity 41 rises to apredetermined level, such as 850' psi. for the specific example,pressure switch as is momentarily actuated to activate the delay timer64. Upon completion of its delay cycle of a predetermined time interval,such as 3 seconds for the specific example, delay timer 6% is adapted toprovide electrical energy through conduit 65 and juncture 75 to solenoid66.

The delay timer is particularly employed in the preferred embodiment ofthis invention since it provides three distinct advantages. Iteliminates the efiects of any pressure surges in any of the fluidconduits inclusive of any surges in the source of high pressure filllld;it gives suflicient time for the blank-holding pressure to build-up so:as to eliminate eiiects of the pressures in the fluid conduits asopposed to the pressure in die recess or cavity 41 land it providessufficient time so as to allow heavy gauge metal blanks to be moved andheld firmly in intimatte contact with the shaped surface 6 of die 7.

Upon energization of solenoid 66, valve 69 is actuated so as to placecomplementary fluid conduit portion 9 1, of

fluid conduit 67 in communicating relationship with heador conduit 50through the complementary fluid conduit portion 92 while simultaneouslyclosing the electrical switch 73. Valve 69 is a three-way valve whichnormally maintains the complementary portions of fluid conduit 67 closedrelative to header conduit 50 and maintains the complementary portion 91of fluid conduit 6-7 adjacent blank 1 in communicating relationship withvent conduit 72.

Subsequent to the actuation of valve 69, the valve is maintained in itsactivated position by means of a complete electrical circuit beingestablished through solenoid 66, switches 76 and 79. With thecomplementary fluid conduit portions 91 and 92 in communicatingrelationship with each other, a blank-expanding pressure reduced bymeans of pressure regulator 71 to a desired blank-expanding pressurelevel, such as 2,800 p.s.i. for the specific example, is applied intothe unjoined portions or laminations 2 of blank 1. As theblank-expanding pressure rises to a predetermined pressure level, suchas 2,800

p.s.i. for the specific example, a pressure switch 655 preset to beactuated at the predetermined blank-expanding pressure level provides amomentary activation of delay timer 85 which alter a predetennined timeinterval, such as seconds for the specific example, is adapted by meanssuch as an appropriate internal switch to transmit an electrical impulsein conduit $6 to its juncture 33. It is to be understood that theblank-holding pressure in die chamber 41 is preferably maintained atconstant pressure, for example 850 p.s.i., by means of suitable pressurerelief valves not shown but readily apparent to those sk lled in theart.

The time interval at which delay timer 85 is preset provides distinctadvantages in the expansion of the hollow or partially laminated blank 1by eliminating effects of surges throughout the fluid conduits. Inaddition, as discussed previously, since a partially laminated pressure-Welded blank has a tendency for the laminations or unjoined portion 2,of blank 1, to be lightly tacked the laminations require a certainpressure level to break their area loose. In the absence of the delayperiod preset in the delay timer 85, the desired pressure level would bereached before blank 1 would be fully expanded. The same advantages ofthis invention are also provided where the design of the partiallaminations or unjoined area contains very narrow or restricted areasthrough which the blankexpanding fluid pressure must go through. Thespecific length of time in which the blank-expanding fluid pressure isrequired to be applied within the partially laminated blank 1 can bereadily determined by one skilled in the art bearing in mind the singlecriterion that the applica tion of the blank-expanding fluid pressure isto be applied for a suflicient length of time to give all laminations orunjoined areas 2 of blank 1 a chance to expand to a uniform height. Allthat is required is to permit the high pressure to build-up throughoutthe hollow interior of blank 1 for a sufiicient length of time to fullyexpand the panel uniformly.

A section of the apparatus with the blank in its expanded configurationis illustrated in FIGURE 3. As can be seen by reference to this figure,the die recess 41 with the blank-expanding fluid pressure therein andhaving a flat upper surface at a height from the upper face of the blankat a distance equal to the desired expanded height of the unjoinedportions contained within the blank. The blank-expanding fluid pressureholds the lower face of the blank firmly and intimately with the shapedsurface 6 of die 7. Upon application of the blank-expanding fluidpressure within unjoined portions or laminations 2 of blank 1, thispressure acting in combination with the blankholding pressure appliedexternally of the blank expands the unjoined portions or laminations 2until they are flattened against the top of the die recess 41. Theresultant shaped panel 93 is provided with flat top bulges to de fine aninternal system of passageways 95 corresponding eases 8 to the patternof unjoined portions or laminations 2 previously contained within blank1.

When delay timer transmits the electrical impulse to juncture 33, theimpulse is in turn transmitted through electrical conduits 32, 63 and 34to simultaneously activate solenoids 30, 61 and 8%), respectively. Whensolenoid 30 is activated, it opens electrical switch 29 permittingswitch 21 to open and valve 14 to close. Upon activation of solenoids 61and 80, valves 47 and 69 are returned to their normal position to ventdie cavity 41 and the interior of blank 1 to the atmosphere to thussimultaneously release the pressures therein. Upon release of fluidpressures within die recess 41 and that employed for expanding blank 1,valve 18, in vent conduit 17 is then manually opened to return die 7 toits open position so as to separate it from die 40 for removal from theexpanded panel.

Although a specific combination of pressure levels has been employed, itis to be understood that various pressure levels, both internally andexternally of the partially laminated blank, and various pressure leveldifferentials are contemplated and may be varied in accordance with thetype of blank employed, the thicknesses of the blank, the degree ofdistention or expansion desired and the shape and configurations of thedistentions to be produced. In accordance with the concept of thisinvention, the operator need merely to make the necessary variations andadjustments until the desired distentions are obtained. The best resultsare obtained for each blank with the desired configuration of thepassageways and the height of the distention at some particularcombination of internal and external pressures and the length of timefor the application of these pressures to be determined in each instanceby the operator for the specific blank and its intended application.

Also, although the preceding example has been described with respect toa simultaneous release of its blankholding and blank-expandingpressures, it is preferred that the release of these two pressures to becontrolled so that a balance or specific ratio is maintained between theventing of the blank-holding and blank-expanding pressures so that thedifference between them will not be greater than the bulging pressure ofthe blank and the collapsing pressures of the desired expandedconfiguration. In accordance therewith, the blank-holding pressurecannot exceed the blank expanding pressure by a quantity equivalent tothe collapsing pressure of the tubes, and the blankexpanding pressurecannot exceed the blank-holding pressure by a quantity equivalent to thebulging pressure of the panel. The bulging pressures and the collapsingpressures can be readily determined by the operator for each type ofblank employed. For example, with reference to the specific examplewhich employed a 0.060 inch thick blank of 1100 type aluminum containinga inch circuity, bulging of these units will occur at about p.s.i. andcollapsing of the resultant expanded passageways will occur at about 350p.s.i. Therefore, for this specific blank, the blank-holding pressureshould not be permitted to exceed the blank-expanding pressure by this350 p.s.i. bulging value. Also, the blank-expanding pressure should notexceed the blank-holding pressure by p.s.i. when the die pressure hasbeen relieved to a level no longer sufficient to hold the expanded blankin the desired contact with the shaped surface 6 of die 7. The rates atwhich the blank-holding and blank-expanding pressures are beingexhausted do not have to be fixed. It is only necessary that they bekept in balance sufficient that the above referred-to conditions aremet. The desired expanded configuration is obtained when the aboveconditions are met wherein the blank-holding and blank-expandingpressures are released at a rate so that at their discharge a differencebetween them is maintained between the bulging pressure of the unit andthe collapsing pressures of the distended system of passageways. Onesystem in which these conditions can be maintained is illustrated inFIGURE 4.

The apparatus illustrated in FIGURE 4 employs basically the sameinflating apparatus described with reference to FIGURE 2 with theexception that an appropraite vent control 97 is connected across ventconduits 72 of valve 69 and vent conduit 52 of valve 4 7. This ventcontrol 97 consists of a passage 98 in communicating relationship withvent conduit 72, and opening into a bore or chamber 9 provided at itsother end with a screwedly attached adjusting plug 1%. The vent controlis also provided with a ball check ltll normally engaging a conical seat102 in the wall portion 163 to normally close the vent control againstescape of the blank-expanding pressure, within the blank, unless thispressure exceeds a predetermined level. The desired pressure level ismaintained within the blank by means of a vented follower 14M and a coilspring 1635' mounted in a bore ass, of the vent control, to act withadjustable compression on ball check ltlll by means of adjusting plugAdjusting plug ms is provided with a suitable slotted end portion lit!for engagement by a suitable tool in order to adjust the de siredpressure levels. A suitable conduit 1% is connected at one end incommunicating relationship with bore 1% of the vent control and at itsother end in communicating relationship into vent 52 of valve 4-7.

At the conclusion of the expanding operations, the valves 47 and as arereturned to their normal position. The discharging blank-holdingpressure supplements the compressive action of spring Md on follower 104to urge ball check lill under a greater pressure into sealingrelationship against conical seat 102. In this manner, theblank-expanding pressure is not permitted to escape until the releasedblank-holding pressure falls to a predetermined level. As will beobvious, fluctuations between the blank-holding and blank-expandingpressures from the desired relation between them will be preventedautomatically by the action of this valve control means. Although in thespecific embodiment illustrated in FIGURE 4, the discharge of theblank-expanding pressures is controlled by the control means inconjunction with the discharge of the venting pressures in vent conduit52, the control means illustrated in FIGURE 4 may also be employed tocontrol the rate of discharge of the blank-holding pressures where thespecific expanding operations so dictate.

FIGURE 5 illustrates another form of controlling the rates of dischargeof the blank-holding and blank-expanding pressures in conjunction withanother embodiment of this invention. This embodiment distinguishes fromthe preceding ones by substituting for pressure switch 68 inblank-expanding fluid conduit m a plurality of delay timers 169 and lit?operatively connected in the expanding apparatus. As previously, delaytimer 64, actuated in response to a predetermined pressure level in diecavity 41, after a predetermined time delay activates solenoid as toactuate valve 65? and maintains the valve in its operativeblank-expanding position and simultaneously closes electric switch '73.Simultaneously with the actuation of valve 6?, after delay timer as hasrun its time cycle, timers 1-99 and 116 are also actuated by beingoperatively connected at junctures ill and 112, respectively, in theelectric conduit 65. Each of the timers 139 and 119 are preset toprovide an electric signal independently from each at different times toactivate solenoids s1 and 8-9 independently.

The embodiment of FIGURE 5 also distinguishes over preceding embodimentsin that solenoid St? is activated by a momentary signal from pressureswitch 13 simultaneously with valve 47 so as to close valve 14 at thesame time that valve 47 is actuated. This is accomplished by operativelyconnecting the solenoid 3% at juncture 113 in electrical conduit 33.Thus, when pressure switch 13 transmits a momentary signal to electricalconduit 33, the solenoid 3th is activated to open switch 29 to break theelectrical circuit to solenoid 2% opening switch 21 and closing valve14. The hydraulic pressure in piston chamber 9 is then maintained untilreleased by opening valve 18.

Where the blank-holding pressure is to be released first, delay timerill-ill is preset to transmit a signal prior to delay timer 1%. Upontransmission of the signal from timer 114) to solenoid 6d, switch 59 isopened to permit the activation of solenoid 51 to result in openingswitch 53 and returning valve 47 to its normal position so as to ventthe blank-holding pressure through vent 5-2. However, in order tocontrol the relationship between the rate at which the blank-holdingpressure is discharged and the subsequent rate of discharge of theblank-expanding pressure through vent 72, both vent conduits 52 and 72are provided with control orifices 114 and 115, respectively, of adiameter having predetermined relationship to the rates of dischargedesired between the fluid pressures. Orifice 114- and timer 1%? are socoordinated that when the pressure level of the blank-holding pressurefalls a predetermined degree at the end of a predetermined timeinterval, delay timer 1% will at that time transmit a signal of activatesolenoid 8% to actuate valve 69 into its normal position to beginrelieving of the blank-expanding pressures. With valves 47 and 69 intheir normal positions, the sizes of the orifices 11 and 115 permit theevacuation of the blank-holding and blank-expanding pressures at adesired relationship between each other. A specific relationship of thesizes of orifices 114 and 115 and the desired time interval in timer 169can be readily determined by considerations well known in the art.

Each of the preceding embodiments employed control means forautomatically releasing only the blank-holding and blank-expandingpressures retaining the hydraulic pressure in piston chamber 9 tomaintain dies 7 and 4%) in the closed position. However, the embodimentof FIGURE 5 denotes additional control means by means of a broken linefor automatically relieving the hydraulic pressures in piston chamber 9.This may be accomplished by adding an additional delay timer 116,operatively connected to valve 118 and adapted to 'be activated by asignal from delay timer as. Delay timer 1 16 is preset so as to transmita signal after a time interval sufficient to insure a completeexhausting of the blank holding and blank-expanding pressures. Thus,when delay timer 116 transmits the signal to open valve 18, vent conduit17 exhausts the die closing pressures in piston chamber 9 to return die7 to its open position for removal of the blank.

Use of the control means to maintain a desired relationship between therates of discharge of the blankholding and blank-expanding pressurespermits the fabrication of a novel blank in accordance with anotheraspect of this invention which will be described with reference to theapparatus of FIGURE 2 employing the control means 97 illustrated inFIGURE 4. In the fabrication of this novel panel, the control means isadjusted by means of slotted adjusting plug 1% to permit the release ofthe blank-holding pressure to be maintained at a magnitude so that acertain amount or" tube height can be expanded on the face of the blankadjacent the shaped surface 6 of die 7. This tube height is controlledby maintaining a specific relationship between the discharge of theblank-holding and blank-expanding pressures. In accordance with thisinvention, it was found by maintaining this relationship, the webportions of blank 1 intermediate tubular configurations were also bulgedout of the face and to the same height as the face of the blank adjacentthe shaped surface 6 of die 7. With reference to the specific exampleemploying the 0.060 inch thick blank of 1100 type aluminum, theblank-holding pressure employed was 300 p.s.i. with the rates ofdischarge maintained so that no additional bulging of the panel tookplace and no collapsing of the expanded blank took place. This novelexpanded panel 117 is illustrated in FIGURE 6 in which the blank-holdingpressure 300 p.s.i. applied through fluid conduit 89 acts against theblank. A blank-expanding pressure of 2,800 p.s.i. is shown appliedinternally of the blank to accomplish expansion while the blank-holdingpressure is applied externally of the blank. This relationship ofpressures maintains and reshapes the expanding blank in such a Way toprovide a fully expanded distention 118 out of the face adjacent dierecess 41 and a partially expanded distention 119 of a substantiallylesser degree than distention 118 out of the face of the blank adjacentshaped surface 6 of die 7. In addition, the portions of the panelbetween the laminations of the blank are deformed out of the face of theblank adjacent shaped surface 6 of die 7 into bulges 120 to extend outof the plane of panel 117 to the same degree as the partially expandeddistention of distention 118.

Although the fabrication of this novel blank has been described inrelation with the application of a blankholding pressure containedwithin a cavitated die, it is to be understood that this blank can alsobe obtained by use of appropriately recessed dies in accordance with theteachings of the aforesaid U.S. Patent 2,690,002. Where the recess diesof the aforesaid patent are employed, the faces of each die areappropriately contoured to provide the desired configuration of thisnovel blank.

This novel panel having web portions bulged out of the same face and tothe same height as the tubular distentions expanded to substantiallylesser degree than the distentions out of the other face of the panelprovide desired advantages over prior type structures. This novel panelprovides increased volumes over an expanded panel having one facesubstantially unexpanded and in addition increases the contact area ofthe partially deformed face of the panel so as to provide an increasedsupporting surface while simultaneously reducing the susceptibility todamage from structures placed thereon.

In the absence of the deformed Web portions, prior art panels employedas a refrigerator evaporator panel were susceptible from damage toarticles such as food and ice cube containers placed thereon. Forexample, with respect to ice cube trays to enter the space betweenadjacent distended passageways so as to collide against one of thepassageways. Such collisions can result in the deformation of theexpanded passage so as to restrict the flow of refrigerant fluid thereindecreasing the efliciency of the evaporator. Also, where the accumulatedfrost on the evaporator is desired to be removed by means such as ascraper, a panel, without the bulged portions is susceptible to punctureby the scraper entering the space between the distended passageways andhitting against one of the distended passages. Such puncture practicallydestroys further use of the panel until repaired. However, with thedeformed web portions of the panel of this invention bulged out of theface to be used as a supporting surface, these bulged web portionsprovide not only an additional contacting surface for support but inaddition provide a desired means to deflect an approaching object so asto reduce the susceptibility to damage.

FIGURE 7 illustrates still another embodiment of this invention ofexpanding a partially laminated blank similar to that depicted in FIGURE2 with the exception that pressure switch 68 and timer 85 aresubstituted by a delay timer 121 adapted to transmit a series of signalsat desired predetermined time intervals after an initial time delay. Inthis embodiment, pressure switch 46 momentarily activates timer 121 toactuate, after a predetermined time delay, valve 69 and close electricswitch 73 so as to inject a blank-expanding pressure into thelaminations 2 of blank 1. However, in this embodiment, delay timer 121is also adapted to transmit a second signal after a predetermined timeinterval subsequent to the transmission of the first signal to activatesolenoids 30, 61 and 80 to return valves 14, 47 and 69, respectively, totheir normal position which relieves the blank-holding andblank-expanding pressures through vent conduits 52 and 72, respectively.The delay desired in delay timer 121 can be readily determined by theoperator to insure a uniform expansion of the laminations within blank1.

FIGURE 8 illustrates a still further embodiment of this inventionsimilar to that of FIGURE 7 from which automatically actuated valve 14and manually actuated valve 18 are substituted by a single automaticallyactuated valve 122. Valve 122 distinguishes from the previous valves inmaintaining its normal position complementary fluid conduit 87 of dieclosing fluid conduit 11 closed with respect to the complementary fluidconduit portions 88 of fluid conduit 11 and maintains complementaryfluid conduit portion 87 in cooperating relationship With vent conduit123. Upon energization of sole noid 20, valve 122 is actuated to closecomplementary conduit portion 87 with respect to venting conduit 123 andto place it in cooperating relationship with its complementary conduitportion 38. This relationship is maintained by the simultaneous closingof electric switch 21. At the completion of the expansion of blank 1,valve 122 is returned to its normal position by the secondary signal ofdelay timer 121 as in the apparatus of FIGURE 7. This embodiment, ofFIGURE 8, provides a simultaneous release of all the applied pressures;die-closing, blank-holding and blank-expanding pressures.

A still another embodiment of this invention is shown in FIGURE 9 whichis similar to the preceding embodiment with the exception that itemploys two delayed time relays 64 and 124 in place of a single relay121. As in the preceding embodiment delay timer 64 is actuated bypressure switch 46 and a predetermined blank-holding pressure totransmit a signal after a predetermined time delay to activate solenoid66 for actuation of valve 69 and to activate the second timer 124 whichafter a predetermined time delay transmits a signal to solenoids 20, 61,and to return valves 122, 47, and 69 simultaneously to their normalposition.

Although the invention has been described with reference to specificembodiments, materials and details, various modifications and changes,Within the scope of this invention, will be apparent to one skilled inthe art and are contemplated to be embraced within the invention.

What is claimed is:

1. An apparatus for fabricating a hollow panel by expansion of a blankhaving an unjoined interior portion contained within outer faces of saidblank comprising a pair of dies relatively movable between open andclosed positions, said dies being adapted to receive said blank in theopen position and to limit the outer expansion thereof in the closedposition, one of said dies having a recess therein adjacent one face ofsaid blank and adapted to be placed in sealing relationship with saidblank when said dies are in a closed position, said recess being deepenough to limit the expansion of said blank to a predetermined height,the other of said dies being substantially smooth for contiguousengagement with the other face of said blank, closure means for openingand closing said dies, a blank-holding conduit connected to said recessto transmit blank-folding fluid thereinto, an expansion conduit meansadapted for connection to said blank for injecting a blank-expandingfluid into said unjoined portion, activating means to operate saidclosure means to close said dies above a predetermined pressure level,means operating in response to a predetermined pressure level of saiddies to inject blank-holding fluid through said recess conduit meansinto said recess at a predetermiend blank-holding pressure, programmingmeans responsive to a predetermined blank-holding pressure fortransmitting a signal after a predetermined time delay, means responsiveto said signal to supply blank-expanding fluid pressure into theunjoined portions of said panel, and means responsive to a predeterminedblank-expanding pressure to release said blank-holding and blank-expaning pressures.

2. An apparatus for fabricating a hollow panel by expansion of a blankhaving an unjoined interior portion contained within outer faces of saidblank comprising a pair of dies relatively movable between open andclosed positions, said dies being adapted to receive said blank in theopen position and to limit the outer expansion thereof in the closedposition, one of said dies having a recess therein adjacent one face ofsaid blank and adapted to be placed in sealing relationship with saidblank when said dies are in a closed position, said recess being deepenough to limit the expansion of said blank to a predetermined height,the other of said dies being substantially smooth for contiguousengagement with the other face of said blank, hydraulic means for movingone of said dies between open and closed positions, a die conduit meansconnected to said hydraulic means for injecting fluid pressure thereintoto move said dies into the open and closed positions, a blank-holdingconduit means connected to said recess to inject blank-holding fluidpressure thereinto, an expansion conduit means adapted for connection tosaid blank for injecting a blank-expanding fluid into said unjoinedportion, activating means to inject die-closing fluid through said diecondut means to operate said hydraulic means at a predetermined pressurelevel suflicient to colse said dies, means operating a response to apredetermined pressure level of said die-closing fluid to injectblank-holding fluid through said recess condiut means into said recessat a predetermined pressure, means operating in response to apredetermined pressure of said blank-holding fluid to inject ablank-expanding fluid pressure into the unjoined portion of said panel,programming means responsive to a predetermined blank-expanding pressurefor transmitting a signal after a predetermined time delay and meansresponsive to said signal to release said blank-holding andblank-expanding pressures.

3. An apparatus for fabricating a hollow panel by expansion of a blankhaving an unjoined interior portion contained within outer faces of saidblank comprising a pair of dies relatively movable between open andclosed positions, said dies being adapted to receive said blank in theopen position and to limit the outer expansion thereof in the closedposition, one of said dies having a recess therein adjacent one face ofsaid blank and adapted to be placed in sealing relationship with saidblank when said dies are in a closed position, said recess being deepenough to limit the expansion of said blank to a predetermined height,the other of said dies being substantially smooth for contiguousengagement with the other face of said blank, hydraulic means for movingone of said dies between open and closed positions, a die conduit meansconnected to said hydraulic means for injecting fluid pressure thereintoto move said dies into the open and closed positions, a blank-holdingconduit means connected to said recess to inject blank-holding fluidpres sure thereinto, an expansion conduit means adapted for connectionto said blank for injecting a blank-expanding fluid into said unjoinedportion, activating means to inject die-closing fluid through said dieconduit means to operate said hydraulic means at a predeterminedpressure level suflicient to close said dies, means operating inresponse to a predetermined pressure level of said die-closing fluid toinject blankholding fluid through said recess conduit means into saidrecess at a predetermined pressure, programming means responsive to apredetermined blankholding pressure to transmit after a predeterminedtime delay a series of signals at predetermined time intervals, meansresponsive to one of said signals to supply blankexpanding fluid intosaid unjoined portions, and means responsive to a subsequent signalafter said one signal of said programming means to release saidblank-holding and blank-expanding pressures.

4. The apparatus of claim 3 including ratio means operatively connectedin communicating relationship with said blank-holding andblank-expanding pressures to release said blank-holding andblank-expanding pressures at a rate so that during discharge thedifference between said blank-holding pressure and said blank-expandingpressure is maintained between the bulging pressure of said blank andthe collapsing pressure of the expanded unjoined portion.

5. An apparatus for fabricating a hollow panel by expansion of a blankhaving an unjoined interior portion contained within outer faces of saidblank comprising a pair of dies relatively movable between open andclosed positions, said dies being adapted to receive said blank in theopen position and to limit the outer expansion thereof in the closedposition, one of said dies having a recess therein adjacent one face ofsaid blank and adapted to be placed in sealing relationship with saidblank when said dies are in a closed position, said recess being deepenough to limit the expansion of said blank to a predetermined height,the other of said dies being substantially smooth for contiguousengagement with the other face of said blank, hydraulic means moving oneof said dies between open and closed positions, a die conduit meansconnected to said hydraulic means for injecting fluid pressure thereintoto move said dies into the open and closed positions, a blank-holdingconduit means connected to said recess to inject blank-holding fluidpressure thereinto, an expansion conduit means adapted for connection tosaid blank for injecting a blank-expanding fluid into said unjoinedportion, activating means to inject die-closing fluid through said dieconduit means to operate said bydraulic means at a predeterminedpressure level sufficient to close said dies, means operating inresponse to a predetermined pressure level of said die-closing fluid toinject blank-holding fluid through said recess conduit means into saidrecess at a predetermined pressure, a first programming means responsiveto a predetermined blank-holding pressure for transmitting a firstsignal after a predetermined time delay, means responsive to first saidsignal to supply blank-expanding pressure into said unjoined portion, asecond programming means responsive to said first signal to transmit asecond signal after a predetermined time delay, and means responsive tosaid second signal to release said blank-holding and blankexpandingpressures.

6. An apparatus for fabricating a hollow panel by expansion of a blankhaving an unjoined interior portion contained within outer faces of saidblank comprising a pair of dies relatively movable between open andclosed positions, said dies being adapted to receive said blank in theopen position and to limit the outer expansion thereof in the closedposition, one of said dies having a recess therein adjacent one face ofsaid blank and adapted to be placed in sealing relationship with saidblank when said dies are in a closed position, said recess being deepenough to limit the expansion of said blank to a predetermined height,the other of said dies being substantially smooth for contiguousengagement with the other face of said blank, hydraulic means for movingone of said dies between open and closed positions, a die conduit meansconnected to said hydraulic means for injecting fluid pressure thereintoto move said dies into the open and closed positions, a blank-holdingconduit means connected to said recess to inject blank-holding fluidpressure thereinto, an expansion conduit means adapted for connection tosaid blank for injecting a blank-expanding fluid into said unjoinedportion, activating means to inject dieclosing fluid through said dieconduit means to operate said hydraulic means at a predeterminedpressure level sufficient to close said di s, means operating inresponse to a predetermined pressure level of said die-closing fluid toinject blank-holding fluid through said recess conduit means into saidrecess at a predetermined pressure, a first programming means responsiveto a predetermined blankholding pressure to transmit a first signalafter a predetermined time delay of at least three seconds, valve meansresponsive to first signal to supply blank-expanding fluid pressure intosaid unjoined portion, a second programming means responsive to apredetermined blank-expanding pressure to transmit a second signal aftera predetermined time delay of at least 10 seconds, means responsive tosaid second signal to release said blank-holding and blank-expandingpressures.

References Cited in the file of this patent UNITED STATES PATENTS 16Gerhardt Apr. 15, 1958 Adams Oct. 14, 1958 Staples Dec. 30, 1958 RiceApr. 29, 1960 Thomas Jan. 3, 1961 Thomas Oct. 10, 1961 OTHER REFERENCESElementary Wiring Diagrams for Machine Analysis, Product Engineering,August 1949.

1. AN APPARATUS FOR FABRICATING A HOLLOW PANEL BY EXPANSION OF A BLANKHAVING AN UNJOINED INTERIOR PORTION CONTAINED WITHIN OUTER FACES OF SAIDBLANK COMPRISING A PAIR OF DIES RELATIVELY MOVABLE BETWEEN OPEN ANDCLOSED POSITIONS, SAID DIES BEING ADAPTED TO RECEIVE SAID BLANK IN THEOPEN POSITION AND TO LIMIT THE OUTER EXPANSION THEREOF IN THE COSEDPOSITION, ONE OF SAID DIES HAVING A RECESS THEREIN ADJACENT ONE FACE OFSAID BLANK AND ADAPTED TO BE PLACED IN SEALING RELATIONSHIP WITH SAIDBLANK WHEN SAID DIES ARE IN A CLOSED POSITION, SAID RECESS BEING DEEPENOUGH TO LIMIT THE EXPANSION OF SAID BLANK TO A PREDETERMINED HEIGHT,THE OTHER OF SAID DIES BEING SUBSTANTIALLY SMOOTH FOR CONTIGUOUSENGAGEMENT WITH THE OTHER FACE OF SAID BLANK, CLOSURE MEANS FOR OPENINGAND CLOSING SAID DIES, A BLANK-HOLDING CONDUIT CONECTED TO SAID RECESSTO TRANSMIT BLANK-FOLDING FLUID THEREINTO, AN EXPANSION CONDUIT MEANSADAPTED FOR CONNECTION TO SAID BLANK FOR INJECTING A BLANK-EXPANDINGFLUID INTO SAID UNJOINED PORTION, ACTIVATING MEANS TO OPERATE SAIDCLOSURE MEANS TO CLOSE SAID DIES ABOVE A PREDETERMINED PRESSURE LEVEL,MEANS OPERATING IN RESPONSE TO A PREDETERMINED PRESSURE LEVEL OF SAIDDIES TO INJECT BLANK-HOLDING FLUID THROUGH SAID RECESS CONDUIT MEANSINTO SAID RECESS AT A PREDETERMINED BLANK-HOLDING PRESSURE, PROGRAMMINGMEANS RESPONSIVE TO A PREDETERMINED BLANK-HOLDING PRESSURE FORTRANSMITTING A SIGNAL AFTER A PREDETERMINED TIME DELAY, MEANS RESPONSIVETO SAID SIGNAL T SUPPLY BLANK-EXPANDING FLUID PRESSURE INTO THE UNJOINEDPORTIONS OF SAID PANEL, AND MEANS RESPONSIVE TO A PEDETERMINEDBLANK-EXPANDING PRESSURE TO RELEASE SAID BLANK-HOLDING ANDBLAND-EXPANDING PRESSURES.